The present invention relates to a recording/reproducing apparatus for a magneto-optical disk and which records and reproduces information on and from a magneto-optical disk using a magnetizing device for applying an external magnetic field to the magneto-optical disk and an optical pickup for irradiating a laser beam onto the magneto-optical disk, and more particularly to a recording/reproducing apparatus for a magneto-optical disk wherein the magnetizing device simply ascends and descends and moves together with the optical pickup while being in contact with the magneto-optical disk.
A magneto-optical disk medium has a recording layer with a vertical anisotropy in which a magnetization direction is arranged in a vertical direction with respect to the surface of the disk by an external magnetic field. The recording layer is made of a magnetic body such as TbFe or TbFeCo.
In the state that the recording layer is magnetized in a certain direction, if a magnetic field is applied in the opposite direction thereof, and the temperature of a portion of the recording layer is raised above the Curie point, the magnetic field is magnetized (written) in the opposite direction when the magnetization state of the temperature-raised portion is demagnetized (erased) and the portion returns to the normal temperature. Also, when the recording layer is irradiated with light, the recording layer has a characteristic of rotating the surface of a polarized light wave by the Kerr effect at the portion where the magnetization direction is reversed.
Therefore, in the magneto-optical recording method, the recording of intended information can be carried out by using a magnetization device such as an electromagnet for applying an external magnetic field to the magneto-optical disk medium, and a light irradiating device for outputting a laser beam having a certain energy. Also, the recorded information can be reproduced by detecting the reflected laser beam of which the polarized wave surface is rotated.
FIGS. 1 and 2 illustrate a recording/reproducing apparatus of a conventional magneto-optical disk for recording and reproducing the information with respect to the magneto-optical disk medium.
In FIG. 1, a magneto-optical disk 2, which is held in a cartridge 2' rotates while being accommodated in a cartridge holder 5 and mounted on a turntable 1a of a spindle motor 1. An optical pickup 7 is placed under the rotating magneto-optical disk 2. Optical pickup 7 is moved by a motor (not shown) and is loaded on a carriage which moves in a radius boundary of disk 2. Over magneto-optical disk 2 is installed a bias magnet 3. Bias magnet 3, as shown in FIG. 2, is supported by a pin 3a which is inserted into a guide slot 6a of a guide wall 6 which is installed on the upper surface of holder 5, and a lever 8 which connects the upper surface with frames 4 and 4'. Accordingly, bias magnet 3 is raised and lowered by the movement of holder 5, so as to be moved closer to magneto-optical disk 2.
Bias magnet 3 is installed to be loaded and unloaded by pin 3a and guide slots 6a in guide wall 6 formed on the top of the cartridge holder 5 installed on frames 4 and 4' to be movable horizontally and vertically, along with the loading and unloading of the cartridge holder 5.
Here, in the conventional recording/reproducing apparatus for a magneto-optical disk, the mechanism for raising and lowering the bias magnet 3 is complicated, such that the apparatus cannot be embodied in a slim size. Also, physical tolerances between guide slots 6a and pin 3a of bias magnet 3 connected thereto allow bias magnet 3 to teeter by as much as the tolerance. Since bias magnet 3 is fixed with respect to magneto-optical disk 2 while being spaced apart by a predetermined distance, they cannot keep their distance fixed due to the vibration of the magneto-optical disk 2.